1. Field of the Invention
The present invention relates to a device, a method, and a non-transitory computer-readable medium for identifying a body part imaged by an imaging unit provided at a distal end of an insertion section of an endoscope.
2. Description Related to the Prior Art
Endoscopes for capturing images of a patient's body cavity are widely known. An insertion section, which incorporates an imaging unit at its distal end, of the endoscope is inserted into the patient's body cavity and the image is captured by the imaging unit. The captured image is displayed on a monitor in real time. A doctor observes an imaged body part through the monitor.
As is well-known, the insertion section of the endoscope is provided with a distal portion, a flexible portion, and a flexible tube disposed in this order from the distal end. The distal portion incorporates the imaging unit. The flexible portion bends to change the direction of the distal portion. The flexible tube is flexible. An operation unit is connected to the proximal end of the insertion section. The operation unit is provided with an operation member (e.g. an angle knob), a shutter button, and the like. The operation member is used for bending the flexible portion. The shutter button allows the imaging unit to record a still image.
In an endoscopic examination, it is necessary for the doctor to perform the observation while knowing the imaged body part, for example, whether the imaged body part is esophagus or stomach, or whether the imaged body part is cardia, pylorus, or gastric angle of the stomach. However, it is difficult to distinguish the body part (e.g. a gastrointestinal tract) being subjected to the endoscopic examination, through visual observation of the image displayed on the monitor, so that the imaged body part may not be identified correctly. To solve this problem, an apparatus for identifying the body part being imaged has been developed.
For example, Japanese Patent No. 4262741 and US2015/0208947 (corresponding to Japanese Patent Laid-Open Publication No. 2014-076174) disclose an apparatus for identifying an imaged body part based on an insertion amount of the insertion section, a bend amount of the insertion section (the flexible portion), and a rotation amount of the insertion section about its axis. In an oral examination, in which the endoscope is inserted through the patient's mouth, such as an examination of an upper gastrointestinal tract, the insertion amount and the rotation amount are detected based on a displacement amount of the insertion section relative to, for example, a mouthpiece attached to the patient's mouth. The bend amount is detected based on, for example, an operation amount of the operation member for bending the flexible portion.
Japanese Patent Laid-Open Publication No. 2012-165838 discloses a technique to identify the imaged body part. According to this technique, three-dimensional image data of the patient's body cavity is generated based on an image acquired from a CT (Computed Tomography) examination or an MRI (Magnetic Resonance Imaging) examination, the insertion amount of the insertion section, the bend amount, and the rotation amount of the insertion section. The three-dimensional image data is compared with an image (current image) being captured, to identify the imaged body part.
However, the method for identifying the imaged body part based on the insertion amount, the bend amount, and the rotation amount as described in the Japanese patent No. 4262741 and the US2015/0208947 has low accuracy in identifying the imaged body part. Even if the insertion amount is the same, the imaged body part may vary from patient to patient, according to the individual difference (body shape, age, gender, or the like). The imaged body part identified based on the insertion amount may be different from the body part actually being imaged.
The rotation amount is detected based on the displacement amount of the insertion section relative to the mouthpiece attached to the patient's mouth. In other words, the rotation amount is detected relative to the direction of the patient's mouth. In case where the direction of the patient's mouth changes (e.g. in case where the patient changes the direction of his face) during the examination, rotation of the insertion section may be detected by error even if the insertion section itself has not been rotated. The bend amount is detected based on the operation amount of the operation member. A bend direction of the flexible portion varies according to a change in the rotation amount, which is the reference for determining the bend direction. For example, a shift of up to 90 degrees may occur between the actual imaging direction and the imaging direction determined based on the detected bend amount and the detected rotation amount.
According to the method described in the Japanese Patent Laid-Open Publication No. 2012-165838, the three-dimensional image data of the patent's body cavity is generated and the imaged body part is identified based on the result of the comparison between the three-dimensional image data and the current image. This method has higher accuracy in identifying the imaged body part than the method described in the Japanese Patent No. 4262741 and US2015/0208947. However, the method described in the Japanese Patent Laid-Open Publication No. 2012-165838 needs time and effort to generate the three-dimensional image data of the patient's body cavity based on the examination data obtained from the CT examination or the MRI examination performed in addition to the endoscopic examination.